Backswimmer

Backswimmers, 1/8 to 1/2 in. (3-12 mm) long, feed on small crustaceans, insect larvae, snails, and sometimes on small fish and tadpoles from which they suck the body juices. They can inflict a painful bite on a human being.

Backswimmers are "true" bugs (so-called because they posses certain features, like a piercing mouthpart).

Backswimmer Illustration
Bali: The Forge Collection
Balinese village cremation
Balistoidei: Development
Ballast Water Risk Assessment for 12 Queensland Ports. Stage 4-Report. Review of Candidate Risk Biota ...

Larvae
Tadpoles are eaten by a variety of predators including bullfrogs, dragonfly, predacious diving beetle, and giant water bug larvae and adults, fishing spiders, and backswimmers (Stockwell 1999).
CONSERVATION CONCERNS ...

Water boatman, common backswimmer
This insect swims upside-down, propelled by two long legs which paddle like oars, making it look like a rowing boat.
Water chevrotain ...

See also: Crustacean, Beetle, Water Bug, Snail, Shrimp